When setting is performed on a base station included in a mobile communication network, an SON (Self Organizing Networks) function for collecting and analyzing quality measurement data and the like from a terminal(s) and a base station(s) and autonomously performing the apparatus setting is used. By using the SON function, it is possible to improve the quality of the network and reduce the operation cost.
For example, an operation performed by an HNB (Home NodeB) or an HeNB (Home eNodeB), which is a home-use compact base station, in which the HNB (Home NodeB) or the HeNB (Home eNodeB) itself automatically performs Plug-and-Play, receives a radio wave (network listening), and determines a radio parameter(s) such as a frequency (EARFCN: E-UTRA Absolute Radio Frequency Channel Number) and a PCI (Physical Cell ID) is considered to be one of the SON operations. Further, an operation in which the status of a radio wave (such as a distribution of pilot channels, a neighboring cell(s), interference, a throughput status, a handover failure rate, a radio load status, and PM (Performance Management)) is measured over a long period, and an OAM parameter(s) is thereby optimized by a statistical technique is also considered to be one of the SON operations.
A configuration of a mobile communication system compliant with an LTE radio communication scheme is explained with reference to FIG. 16. An eNB 10, an eNB 11, and an eNB 12 are base stations compliant with the LTE radio communication scheme. An interface between eNBs is called “X2-interface” (see Non-patent literature 1: 3G3GPP TS36.300). An EM 14 is an Element Manager that controls the eNBs, and an NM 15 is a higher-level apparatus of the EM 14 on the OAM, and represents a Network Manager that maintains and monitors the entire network. An MME/S-GW 13 represents a core network, and performs movement management control and session management control. The interface between an eNB and the MME/S-GW is defined as “S1-interface”.
Next, an OAM reference model disclosed in Non-patent literature 2 (3GPP TS32.101) is explained with reference to FIG. 17. In this figure, respective definitions for an NM (Network Manager), an EM (Element Manager), and an NE (Network Element) are based on 3GPP TS32.101.
NEs 21 to 25 are Network Elements. For example, an eNB (E-UTRAN NodeB), an HeNB, a NodeB, an RNC, and an HNB (Home NodeB) correspond to these elements. DMs 31 to 33 are Domain Managers, and hold a Network Element management function and a sub-network domain management function. EMs 34 to 37 are Element Managers, and provide a Network Element management function. NMs 41 and 42 are Network Managers and are located on a higher level of the EMs. The NMs 41 and 42 manages a network supported by the EMs. When an EM function is accommodated in an NE, the NE is directly accessed by the NM. The NMs 41 and 42 are connected to Enterprise Systems 50 formed by a server apparatus and so on.
Among others, the interface between an EM and an NM or between an NE having an EM function and an NM is defined as a “Type-2 interface”. It is also defined as an “ITF-N (North bound interface)”, which is an open interface defined in the 3GPP standardization specifications series.
Next, an SON solution implemented in the above-described OAM reference model will be explained. In the SON solution, there are three methods, i.e., a Centralised SON, a Distributed SON, and a Hybrid SON as mentioned in Non-patent literature 3 (3GPP TS32.500 Ver10.1.0). The Centralised SON is an SON solution in which an SON algorithm is implemented in an OAM system. There are two types of the Centralised SON, i.e., an NM-Centralised SON in which an SON algorithm is implemented in a Network Management level and an EM-Centralised SON in which an SON algorithm is implemented in an Element Management level. The Distributed SON is an SON solution in which an SON algorithm is implemented in a Network Element level. Further, the Hybrid SON is an SON solution in which an SON algorithm is implemented in a plurality of levels including an NE, or an EM and an NM.
These SON solutions are appropriately selected according to the details of the automatic setting, the OAM target apparatus to be automatically optimized, the SON algorithm, or the required performance. Further, the SON solution is implemented in a vendor apparatus, i.e., a communication apparatus.
In the case of the Distributed SON, since the SON algorithm is implemented in an NE, the OAM parameters can be immediately changed. Therefore, the Distributed SON is suitable to optimize the OAM parameters in real-time. However, in order for the NE itself to optimize the OAM parameters, the NE needs to frequently collect information from neighboring NEs by using protocol messages. Therefore, when the Distributed SON is performed, the number of signalings between NEs increases. Further, there is a restriction that the range the NE can recognize is limited to cells adjacent to the NE or to the range of cells which such adjacent cells are adjacent to.
In contrast, in the Centralised SON, a plurality of NEs in a wide range can be collectively managed in a centralized manner and their statistical information can be used. Therefore, the Centralised SON is suitable to optimize the entire network at long intervals. Further, there is a merit that there is no need to use signaling such as an X2AP-message between NEs.
In a network, there is a possibility that a plurality of vendor apparatuses (such as NEs, EMs, and NMs) are used and a different SON solution is used for each apparatus by using an algorithm (SON algorithm) or an SON performing method unique to the vendor.
For example, as mentioned in Non-patent literature 4 (TR36.902), as a PCI assignment optimization method, it is necessary to assign PCIs so that PCI Collision-free and PCI Confusion-free are guaranteed. However, whether the PCI assignment method should be implemented by the Distributed SON, the Centralised SON, or the Hybrid SON is dependent on the implementation of the apparatus vendor. That is, when the PCI assignment optimization algorithm is implemented on the NE side, it is implemented by the Distributed SON. Further, when the PCI assignment optimization algorithm is implemented in the EM or the NM, it is implemented by the Centralised SON. Further, when the PCI assignment optimization algorithm is implemented in both the NE and the EM/NM, it is implemented by the Hybrid SON. As described above, how it is implemented is dependent on the vendor implementation.
As typical use cases of the SON (SON functions), PCI assignment optimization, ANR (Automatic Neighbour Relation), MRO (Mobility Robustness Optimisation), MLB (Mobility Load Balancing), RACH Optimisation, Self Healing, ICIC (Inter-cell Interference Coordination), CoC (Cell outage Compensation) and so on are defined in 3GPP specifications (3GPP TS36.300 Ver10.0.0, TR36.902 V9.3.1, TS32.500 Ver10.0.0, Non-patent literature 5: TS32.541 Ver10.0.0 and so on).
Further, as defined in TR36.902, the PCI Collision-free is to guarantee that PCIs are unique in an area covered by a cell. Further, the PCI confusion-free is to guarantee that PCIs are unique in neighboring cells.